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inform7/docs/BasicInformKit/S-rtp.html
Graham Nelson d6e8609db1 Fixes for remaining issues arising from PR#106
2023-07-04 18:37:04 +01:00

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>RTP Template</title>
<link href="../docs-assets/Breadcrumbs.css" rel="stylesheet" rev="stylesheet" type="text/css">
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<link href="../docs-assets/Fonts.css" rel="stylesheet" rev="stylesheet" type="text/css">
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</head>
<body class="commentary-font">
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<h1><a href="../index.html">
<img src="../docs-assets/Inform.png" height=72">
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<main role="main">
<!--Weave of 'RTP Template' generated by Inweb-->
<div class="breadcrumbs">
<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../extensions.html">Kits</a></li><li><a href="index.html">BasicInformKit</a></li><li><b>RTP Template</b></li></ul></div>
<p class="purpose">To issue run-time problem messages, and to perform some run-time type checking which may issue such messages.</p>
<ul class="toc"><li><a href="S-rtp.html#SP1">&#167;1. Reporting</a></li><li><a href="S-rtp.html#SP2">&#167;2. Low-Level Errors</a></li><li><a href="S-rtp.html#SP3">&#167;3. Argument Type Checking Failed</a></li><li><a href="S-rtp.html#SP4">&#167;4. Return Type Checking Failed</a></li><li><a href="S-rtp.html#SP5">&#167;5. Whether Provides</a></li><li><a href="S-rtp.html#SP6">&#167;6. Scan Property Metadata</a></li><li><a href="S-rtp.html#SP7">&#167;7. Read Property</a></li><li><a href="S-rtp.html#SP8">&#167;8. Write Property</a></li><li><a href="S-rtp.html#SP9">&#167;9. Printing Property Names</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. Reporting. </b>All RTPs are produced by calling the following routine, which takes one
compulsory argument: <span class="extract"><span class="extract-syntax">n</span></span>, the RTP number. When I7 is being used with the
Inform user interface, it's important that these numbers correspond to the
explanatory web pages stored within the interface application: those in
turn are created by the <span class="extract"><span class="extract-syntax">inrtps</span></span> utility. The interface knows to display
these pages because it parses the printed output during play to look for
the text layout produced by the following routine: so do not reformat
RTPs without ensuring that corresponding changes have been made to the
Inform user interface applications.
</p>
<p class="commentary">The arguments <span class="extract"><span class="extract-syntax">par1</span></span>, <span class="extract"><span class="extract-syntax">par2</span></span> and <span class="extract"><span class="extract-syntax">par3</span></span> are optional parameters clarifying the
message; <span class="extract"><span class="extract-syntax">ln</span></span> is an optional parameter specifying a paragraph number in the
original source text (though in fact I7 does not use this at present).
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">Array</span><span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax"> --&gt; (-1) </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax"> </span><span class="identifier-syntax">n</span><span class="plain-syntax"> </span><span class="identifier-syntax">par1</span><span class="plain-syntax"> </span><span class="identifier-syntax">par2</span><span class="plain-syntax"> </span><span class="identifier-syntax">par3</span><span class="plain-syntax"> </span><span class="identifier-syntax">ln</span><span class="plain-syntax"> </span><span class="identifier-syntax">file</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;0 == -1) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;0 = </span><span class="identifier-syntax">n</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;1 = </span><span class="identifier-syntax">par1</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;2 = </span><span class="identifier-syntax">par2</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;3 = </span><span class="identifier-syntax">par3</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;4 = </span><span class="identifier-syntax">ln</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;5 = </span><span class="identifier-syntax">file</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RunTimeProblemShow</span><span class="plain-syntax">();</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">ClearRTP</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;0 = -1;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;6 = </span><span class="reserved-syntax">false</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">SuspendRTP</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;6 = </span><span class="reserved-syntax">true</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">ResumeRTP</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;6 = </span><span class="reserved-syntax">false</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">RunTimeProblemShow</span><span class="plain-syntax"> </span><span class="identifier-syntax">n</span><span class="plain-syntax"> </span><span class="identifier-syntax">par1</span><span class="plain-syntax"> </span><span class="identifier-syntax">par2</span><span class="plain-syntax"> </span><span class="identifier-syntax">par3</span><span class="plain-syntax"> </span><span class="identifier-syntax">ln</span><span class="plain-syntax"> </span><span class="identifier-syntax">file</span><span class="plain-syntax"> </span><span class="identifier-syntax">i</span><span class="plain-syntax"> </span><span class="identifier-syntax">c</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;0 == -1 </span><span class="reserved-syntax">or</span><span class="plain-syntax"> -2) </span><span class="reserved-syntax">return</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;6) </span><span class="reserved-syntax">return</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">n</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;0;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">par1</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;1;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">par2</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;2;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">par3</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;3;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">ln</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;4;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">file</span><span class="plain-syntax"> = </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;5;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_Buffer</span><span class="plain-syntax">--&gt;0 = -2;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">new_line</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"*** Run-time problem P"</span><span class="plain-syntax">, </span><span class="identifier-syntax">n</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ln</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">" (at paragraph "</span><span class="plain-syntax">, </span><span class="identifier-syntax">ln</span><span class="plain-syntax">, </span><span class="string-syntax">" in "</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">file</span><span class="plain-syntax"> == </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"the source text"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">ShowOneExtension</span><span class="plain-syntax">(</span><span class="identifier-syntax">file</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">")"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">": "</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">switch</span><span class="plain-syntax">(</span><span class="identifier-syntax">n</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_IMPREL</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to access an inappropriate relation for "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">", violating '"</span><span class="plain-syntax">, (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">RlnGetF</span><span class="plain-syntax">(</span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="identifier-syntax">RR_DESCRIPTION</span><span class="plain-syntax">), </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TOOMANYRULEBOOKS</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Too many rulebooks in simultaneous use.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_BADPROPERTY</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to access non-existent property for "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">".^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_UNPROVIDED</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Since "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">" is not allowed the property ~"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintPropertyName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="string-syntax">"~, it is against the rules to try to use it.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_UNSET</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Although "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">" is allowed to have the property ~"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintPropertyName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="string-syntax">"~, no value was ever given, so it can't now be used.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TOOMANYACTS</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Too many activities are going on at once.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_CANTABANDON</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to abandon an activity which wasn't going on.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_CANTEND</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to end an activity which wasn't going on.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_DIVZERO</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"You can't divide by zero.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_BADVALUEPROPERTY</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to access property for a value which didn't fit: "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"if this were a number it would be "</span><span class="plain-syntax">, </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">".^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOCOL</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to look up a non-existent column in the table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOCORR</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to look up a non-existent correspondence in the table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOROW</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to look up a non-existent row in the table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOENTRY</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to look up a non-existent entry at column "</span><span class="plain-syntax">, </span><span class="identifier-syntax">par2</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">", row "</span><span class="plain-syntax">, </span><span class="identifier-syntax">par3</span><span class="plain-syntax">, </span><span class="string-syntax">" of the table '"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOTABLE</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to blank out a row from a non-existent table (value "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">").^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOTABLE2</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to access an entry from a non-existent table.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOMOREBLANKS</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to choose a blank row in a table with none left: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_NOROWS</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to choose a random row in an entirely blank table: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_CANTRUNTHROUGH</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to repeat through a table in a tricky column order: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_CANTSORT</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to sort a table whose ordering must remain fixed: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_CANTSAVE</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to save a table to a file whose data is unstable: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_WONTFIT</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"File being read has too many rows or columns to fit into table: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TABLE_BADFILE</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"File being read is not a previously saved table: table '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintTableName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_ROUTELESS</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to find route or count steps through an implicit</span>
<span class="string-syntax"> relation.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_PROPOFNOTHING</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to use a property of the 'nothing' non-object: property "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">PrintPropertyName</span><span class="plain-syntax">) </span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="string-syntax">"^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_DECIDEONWRONGKIND</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to 'decide on V' where V is the wrong kind of object.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_DECIDEONNOTHING</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to 'decide on nothing'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_LOWLEVELERROR</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Low level error.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_LISTWRITERMEMORY</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"The list-writer has run out of memory.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_MSTACKMEMORY</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"The memory stack is exhausted.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TYPECHECK</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Phrase applied to an incompatible kind of value.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_FILEIOERROR</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Error handling external file.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_HEAPERROR</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Memory allocation proved impossible.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_LISTRANGEERROR</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to use list item which does not exist.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_LISTSIZENEGATIVE</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to resize list to "</span><span class="plain-syntax">, </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">" entries - there must "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"always be 0 or more.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_REGEXPSYNTAXERROR</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Syntax error in regular expression.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_NEGATIVEROOT</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"You can't take the square root of a negative number.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_CANTITERATE</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"You can't implicitly repeat through the values of this kind: "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"a problem arising from a description which started out here - ~"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">"~.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_WRONGASSIGNEDKIND</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to set a variable to the wrong kind of object: "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"you wrote '"</span><span class="plain-syntax">, (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="string-syntax">"', which sets the value to "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">" - but that doesn't have the kind '"</span><span class="plain-syntax">, (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">par3</span><span class="plain-syntax">, </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_RELKINDVIOLATION</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to change a relation for objects with the wrong kinds: "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">RlnGetF</span><span class="plain-syntax">(</span><span class="identifier-syntax">par3</span><span class="plain-syntax">, </span><span class="identifier-syntax">RR_DESCRIPTION</span><span class="plain-syntax">), </span><span class="string-syntax">", but you tried to "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"relate (or unrelate) "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="string-syntax">" to "</span><span class="plain-syntax">, (</span><span class="identifier-syntax">the</span><span class="plain-syntax">) </span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="string-syntax">".^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_TEXTTOKENTOOHARD</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"This use of '[text]' is too complicated.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_RELATIONCHANGEIMPOSSIBLE</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"This change of the relation's nature is impossible in play.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTP_RELMINIMAL</span><span class="plain-syntax">:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"This operation can't be done with the relation '"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">RlnGetF</span><span class="plain-syntax">(</span><span class="identifier-syntax">par3</span><span class="plain-syntax">, </span><span class="identifier-syntax">RR_DESCRIPTION</span><span class="plain-syntax">), </span><span class="string-syntax">"'.^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RunTimeProblemShowWM</span><span class="plain-syntax">(</span><span class="identifier-syntax">n</span><span class="plain-syntax">, </span><span class="identifier-syntax">par1</span><span class="plain-syntax">, </span><span class="identifier-syntax">par2</span><span class="plain-syntax">, </span><span class="identifier-syntax">par3</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. Low-Level Errors. </b>The following is a residue from the old I6 library, and most of its possible
messages can't be seen in I7 use &mdash; for instance I7 has no timers or daemons,
so error 4 is out of the question. But we retain the routine because the
veneer code added by I6 requires it to be present.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">Constant</span><span class="plain-syntax"> </span><span class="identifier-syntax">MAX_TIMERS</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">RunTimeError</span><span class="plain-syntax"> </span><span class="identifier-syntax">n</span><span class="plain-syntax"> </span><span class="identifier-syntax">p1</span><span class="plain-syntax"> </span><span class="identifier-syntax">p2</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> #</span><span class="identifier-syntax">Ifdef</span><span class="plain-syntax"> </span><span class="identifier-syntax">DEBUG</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"** Library error "</span><span class="plain-syntax">, </span><span class="identifier-syntax">n</span><span class="plain-syntax">, </span><span class="string-syntax">" ("</span><span class="plain-syntax">, </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">","</span><span class="plain-syntax">, </span><span class="identifier-syntax">p2</span><span class="plain-syntax">, </span><span class="string-syntax">") **^** "</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">switch</span><span class="plain-syntax"> (</span><span class="identifier-syntax">n</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="constant-syntax">1</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"preposition not found (this should not occur)"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">2</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Property value not routine or string: ~"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">property</span><span class="plain-syntax">) </span><span class="identifier-syntax">p2</span><span class="plain-syntax">, </span><span class="string-syntax">"~ of ~"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">name</span><span class="plain-syntax">) </span><span class="identifier-syntax">p1</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"~ ("</span><span class="plain-syntax">, </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">")"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">3</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Entry in property list not routine or string: ~"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">property</span><span class="plain-syntax">) </span><span class="identifier-syntax">p2</span><span class="plain-syntax">, </span><span class="string-syntax">"~ list of ~"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> (</span><span class="identifier-syntax">name</span><span class="plain-syntax">) </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">"~ ("</span><span class="plain-syntax">, </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">")"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">4</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Too many timers/daemons are active simultaneously.</span>
<span class="string-syntax"> The limit is the library constant MAX_TIMERS (currently "</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">MAX_TIMERS</span><span class="plain-syntax">, </span><span class="string-syntax">") and should be increased"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">5</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Object ~"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">name</span><span class="plain-syntax">) </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">"~ has no ~time_left~ property"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">7</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"The object ~"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">name</span><span class="plain-syntax">) </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">"~ can only be used as a player object if it has</span>
<span class="string-syntax"> the ~number~ property"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">8</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Attempt to take random entry from an empty table array"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">9</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">" is not a valid direction property number"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">10</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"The player-object is outside the object tree"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">11</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"The room ~"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">name</span><span class="plain-syntax">) </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">"~ has no ~description~ property"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">12</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"Tried to set a non-existent pronoun using SetPronoun"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="constant-syntax">13</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"A 'topic' token can only be followed by a preposition"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">default</span><span class="plain-syntax">: </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"(unexplained)"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">" **^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> #</span><span class="identifier-syntax">Ifnot</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"** Library error "</span><span class="plain-syntax">, </span><span class="identifier-syntax">n</span><span class="plain-syntax">, </span><span class="string-syntax">" ("</span><span class="plain-syntax">, </span><span class="identifier-syntax">p1</span><span class="plain-syntax">, </span><span class="string-syntax">","</span><span class="plain-syntax">, </span><span class="identifier-syntax">p2</span><span class="plain-syntax">, </span><span class="string-syntax">") **^"</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> #</span><span class="identifier-syntax">Endif</span><span class="plain-syntax">; </span><span class="comment-syntax">DEBUG</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTP_LOWLEVELERROR</span><span class="plain-syntax">);</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. Argument Type Checking Failed. </b>This is called when run-time type checking for the argument of a phrase
fails, so that no definition for the phrase can be applied.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">ArgumentTypeFailed</span><span class="plain-syntax"> </span><span class="identifier-syntax">line</span><span class="plain-syntax"> </span><span class="identifier-syntax">file</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTP_TYPECHECK</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="identifier-syntax">line</span><span class="plain-syntax">, </span><span class="identifier-syntax">file</span><span class="plain-syntax">);</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. Return Type Checking Failed. </b>Similarly, though in a more restricted set of circumstances. Inform can usually
prove that the value returned by a phrase matches its supposed kind, but
because of the deliberately weak type-checking within the kind of value
"object" it will allow a broader kind of object to be returned when the
requirement is for a narrower one. In such cases, it checks the result with
the following routine. The value <span class="extract"><span class="extract-syntax">V</span></span> is a valid "object", but that means
it can be <span class="extract"><span class="extract-syntax">nothing</span></span>, and we must check that it matches a given I7 kind <span class="extract"><span class="extract-syntax">K</span></span>
(where <span class="extract"><span class="extract-syntax">nothing</span></span> is not valid).
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">CheckKindReturned</span><span class="plain-syntax"> </span><span class="identifier-syntax">V</span><span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">V</span><span class="plain-syntax"> </span><span class="reserved-syntax">ofclass</span><span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">V</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">V</span><span class="plain-syntax"> == </span><span class="reserved-syntax">nothing</span><span class="plain-syntax">) </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTP_DECIDEONNOTHING</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTP_DECIDEONWRONGKIND</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">V</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. Whether Provides. </b>This routine defines the phrase "if O provides P": there are three tests
to pass, and if any of the three fail, we return <span class="extract"><span class="extract-syntax">false</span></span>. (The <span class="extract"><span class="extract-syntax">issue_rtp</span></span>
flag, causing RTPs to be issued depending on which test fails, is never set
when the routine is simply testing the condition.)
</p>
<p class="commentary">Firstly, P has to be a property known to I7. Secondly, there has to be
permission either for this individual object to have it, or for its kind to
have it, or its kind's kind, and so on. Thirdly, the object has to actually
have the property in question at an I6 level &mdash; having permission to have
it doesn't mean it actually does have.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">ProvidesProperty</span><span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax"> </span><span class="identifier-syntax">obj</span><span class="plain-syntax"> </span><span class="identifier-syntax">q</span><span class="plain-syntax"> </span><span class="identifier-syntax">issue_rtp</span><span class="plain-syntax"> </span><span class="identifier-syntax">a</span><span class="plain-syntax"> </span><span class="identifier-syntax">l</span><span class="plain-syntax"> </span><span class="identifier-syntax">holder</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> == </span><span class="identifier-syntax">OBJECT_TY</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ScanPropertyMetadata</span><span class="plain-syntax">(</span><span class="identifier-syntax">obj</span><span class="plain-syntax">, </span><span class="identifier-syntax">q</span><span class="plain-syntax">, </span><span class="constant-syntax">4</span><span class="plain-syntax">)) </span><span class="reserved-syntax">jump</span><span class="plain-syntax"> </span><span class="identifier-syntax">PermissionFound</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">obj</span><span class="plain-syntax"> </span><span class="reserved-syntax">provides</span><span class="plain-syntax"> </span><span class="identifier-syntax">KD_Count</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">l</span><span class="plain-syntax"> = </span><span class="identifier-syntax">obj</span><span class="plain-syntax">.</span><span class="identifier-syntax">KD_Count</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">while</span><span class="plain-syntax"> (</span><span class="identifier-syntax">l</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">a</span><span class="plain-syntax"> = </span><span class="identifier-syntax">l</span><span class="plain-syntax">*2;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ScanPropertyMetadata</span><span class="plain-syntax">(</span><span class="identifier-syntax">KindHierarchy</span><span class="plain-syntax">--&gt;</span><span class="identifier-syntax">a</span><span class="plain-syntax">, </span><span class="identifier-syntax">q</span><span class="plain-syntax">, </span><span class="constant-syntax">4</span><span class="plain-syntax">)) </span><span class="reserved-syntax">jump</span><span class="plain-syntax"> </span><span class="identifier-syntax">PermissionFound</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">l</span><span class="plain-syntax"> = </span><span class="identifier-syntax">KindHierarchy</span><span class="plain-syntax">--&gt;(</span><span class="identifier-syntax">a</span><span class="plain-syntax">+1);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ScanPropertyMetadata</span><span class="plain-syntax">(</span><span class="identifier-syntax">K0_kind</span><span class="plain-syntax">, </span><span class="identifier-syntax">q</span><span class="plain-syntax">, </span><span class="constant-syntax">4</span><span class="plain-syntax">)) </span><span class="reserved-syntax">jump</span><span class="plain-syntax"> </span><span class="identifier-syntax">PermissionFound</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">issue_rtp</span><span class="plain-syntax">) </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTP_UNPROVIDED</span><span class="plain-syntax">, </span><span class="identifier-syntax">obj</span><span class="plain-syntax">, </span><span class="identifier-syntax">q</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">rfalse</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> .</span><span class="identifier-syntax">PermissionFound</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> &gt;&gt; </span><span class="identifier-syntax">obj</span><span class="plain-syntax"> </span><span class="reserved-syntax">provides</span><span class="plain-syntax"> </span><span class="identifier-syntax">q</span><span class="plain-syntax">) </span><span class="reserved-syntax">rtrue</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">issue_rtp</span><span class="plain-syntax">) </span><span class="identifier-syntax">RunTimeProblem</span><span class="plain-syntax">(</span><span class="identifier-syntax">RTP_UNSET</span><span class="plain-syntax">, </span><span class="identifier-syntax">obj</span><span class="plain-syntax">, </span><span class="identifier-syntax">q</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">rfalse</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
<span class="plain-syntax">[ </span><span class="identifier-syntax">PrintPropertyName</span><span class="plain-syntax"> </span><span class="identifier-syntax">p</span><span class="plain-syntax"> </span><span class="identifier-syntax">textual</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">p</span><span class="plain-syntax">&lt;0) </span><span class="identifier-syntax">p</span><span class="plain-syntax"> = ~</span><span class="identifier-syntax">p</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">textual</span><span class="plain-syntax"> = </span><span class="identifier-syntax">p</span><span class="plain-syntax">--&gt;3;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> (</span><span class="reserved-syntax">string</span><span class="plain-syntax">) </span><span class="identifier-syntax">textual</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. Scan Property Metadata. </b>The supplied metadata table is a series of zero-terminated lists of objects
(or class objects, representing I7 kinds). Each such list corresponds to a single
property; the position in the table is called the "offset" for the property.
The following searches from a given offset.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">ScanPropertyMetadata</span><span class="plain-syntax"> </span><span class="identifier-syntax">obj</span><span class="plain-syntax"> </span><span class="identifier-syntax">property_metadata</span><span class="plain-syntax"> </span><span class="identifier-syntax">off</span><span class="plain-syntax"> </span><span class="identifier-syntax">i</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="identifier-syntax">i</span><span class="plain-syntax">=</span><span class="identifier-syntax">off</span><span class="plain-syntax">: </span><span class="identifier-syntax">property_metadata</span><span class="plain-syntax">--&gt;</span><span class="identifier-syntax">i</span><span class="plain-syntax"> &gt;= </span><span class="constant-syntax">0</span><span class="plain-syntax">: </span><span class="identifier-syntax">i</span><span class="plain-syntax">++)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">obj</span><span class="plain-syntax"> == </span><span class="identifier-syntax">property_metadata</span><span class="plain-syntax">--&gt;</span><span class="identifier-syntax">i</span><span class="plain-syntax">) </span><span class="reserved-syntax">rtrue</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">rfalse</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>&#167;7. Read Property. </b>Some value properties belong to other values (those created in tables), and
these are stored indirectly through a pseudo-object <span class="extract"><span class="extract-syntax">V</span></span> &mdash; an I6 object which
is not part of the world model, and not a valid I7 "object" value, but which is
used in order that properties belonging to values
are still I6 property numbers. <span class="extract"><span class="extract-syntax">V.P</span></span> is the table column address for this
property; <span class="extract"><span class="extract-syntax">obj</span></span> is then a value for the kind of value created by the table, so
it is used as an index into the table column to get the address of the memory
location storing the property value.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">GProperty</span><span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax"> </span><span class="identifier-syntax">V</span><span class="plain-syntax"> </span><span class="identifier-syntax">pr</span><span class="plain-syntax"> </span><span class="identifier-syntax">err</span><span class="plain-syntax"> </span><span class="identifier-syntax">holder</span><span class="plain-syntax"> </span><span class="identifier-syntax">val</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ProvidesProperty</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">V</span><span class="plain-syntax">, </span><span class="identifier-syntax">pr</span><span class="plain-syntax">, </span><span class="constant-syntax">1</span><span class="plain-syntax">-</span><span class="identifier-syntax">err</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> &gt;&gt; </span><span class="identifier-syntax">V</span><span class="plain-syntax"> . </span><span class="identifier-syntax">pr</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>&#167;8. Write Property. </b>This routine's name must consist of the read-value-property routine's name
with the prefix <span class="extract"><span class="extract-syntax">Write</span></span>, as that is how a reference to such a property is
converted from an rvalue to an lvalue.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">WriteGProperty</span><span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax"> </span><span class="identifier-syntax">V</span><span class="plain-syntax"> </span><span class="identifier-syntax">pr</span><span class="plain-syntax"> </span><span class="identifier-syntax">val</span><span class="plain-syntax"> </span><span class="identifier-syntax">holder</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ProvidesProperty</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">V</span><span class="plain-syntax">, </span><span class="identifier-syntax">pr</span><span class="plain-syntax">, </span><span class="reserved-syntax">true</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax"> &gt;&gt; </span><span class="identifier-syntax">V</span><span class="plain-syntax"> . </span><span class="identifier-syntax">pr</span><span class="plain-syntax"> = </span><span class="identifier-syntax">val</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax">];</span>
</pre>
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>&#167;9. Printing Property Names. </b>Inform doesn't print property names prettily; it more or less prints them
only as decimal numbers.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">PROPERTY_TY_Say</span><span class="plain-syntax"> </span><span class="identifier-syntax">v</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">print</span><span class="plain-syntax"> </span><span class="string-syntax">"property "</span><span class="plain-syntax">, </span><span class="identifier-syntax">v</span><span class="plain-syntax">;</span>
<span class="plain-syntax">];</span>
</pre>
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